Conventionally, there is known a CCTV (Closed Circuit Tele-Vision) system in which a video captured by a surveillance camera is encoded by an encoder and transmitted through a transmission line such as an IP network or the like. In a video surveillance system such as the CCTV system, in order to make it possible to check a status of a disaster in detail from an image (video) of a disaster area at the time of monitoring a crisis and a disaster, it is recently general to encode a video captured by an HD (High Definition) compliant surveillance camera by a HD compliant encoder and transmit the HD video through a transmission line.
However, an SD video captured by a conventional SD (Standard Definition) compliant analog camera is still widely used.
Patent Document 1 discloses a video transmission system capable of making the quantity of video data for a transmission line proper and suppressing delays and missing parts of video images effectively. Further, Patent Document 1 discloses a technique for compressing and encoding videos inputted from a plurality of surveillance cameras connected to Web encoders and transmitting the video data while maintaining a desired quality.
Patent Document 1: Japanese Patent Application Publication No. 2005-051517
In a conventional video surveillance system including the system disclosed in Patent Document 1, it is general to provide integrated LAN switches and encoders as many as the number of the surveillance cameras in order to transmit videos captured by the surveillance cameras through an IP network. When the number of the surveillance cameras is increased, the number of the encoders is also increased. Therefore, a transmission band, an installation location, a cost and the like may be restricted.
In the case of replacing a conventional video surveillance system for transmitting an SD video captured by an SD compliant analog camera with an HD compliant video surveillance system, there are required an HD compliant surveillance camera, an HD compliant encoder and an HD compliant decoder. Accordingly, an equipment investment cost is increased.